System and Method for Sinusoidal Output and Integrated EMC Filtering in a Motor Drive

ABSTRACT

A motor drive that outputs a sinusoidal waveform utilizes power switching devices operable at high switching frequencies. The switching devices may be operated, for example, between twenty kilohertz and one megahertz. A first filter is included at the output of the motor drive which has a bandwidth selected to attenuate voltage components at the output which are at the switching frequency or multiples thereof such that the output voltage waveform is generally sinusoidal. Additional filtering is included within the motor drive to establish a circulation path for common mode currents within the motor drive. Further, a shield is provided adjacent to those components within the motor drive that may experience voltage or current waveforms at the switching frequency or multiples thereof to cause radiated emissions to establish eddy currents within the EMI shield rather than passing through the shield into the environment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 16/580,736 filed Sep. 24, 2019, the entire contentsof which is incorporated herein by reference.

BACKGROUND INFORMATION

The subject matter disclosed herein relates to motor drive topologieswith an improved output voltage waveform supplied by the motor drive.More specifically, the motor drive provides a sinusoidal output voltagewaveform while containing radiated and conducted electromagneticemissions within the motor drive.

As is known to those skilled in the art, motor drives are utilized tocontrol operation of a motor. According to one common configuration, amotor drive includes a DC bus having a DC voltage of suitable magnitudefrom which an AC voltage may be generated and provided to an AC motor.The DC voltage may be provided as an input to the motor drive or,alternately, the motor drive may include a converter section whichconverts an AC voltage input to the DC voltage present on the DC bus.The converter section may be passive, including conventional dioderectification, or active, including controlled power electronicswitching devices, either of which may convert an AC voltage input to aDC voltage for the DC bus. The power electronic switching devices in anactive rectifier may be selected from transistors, such as insulatedgate bipolar transistors (IGBTs) or metal oxide semiconductorfield-effect transistors (MOSFETs), thyristors, or silicon-controlledrectifiers (SCRs). The power electronic switching device may alsoinclude a reverse conduction power electronic device, such as afree-wheeling diode, connected in parallel across the power electronicswitching device. The reverse conduction power electronic device isconfigured to conduct during time intervals in which the powerelectronic switching device is not conducting. A controller in the motordrive generates switching signals to selectively turn on or off eachswitching device to generate a desired DC voltage on the DC bus.

The motor drive receives a command signal which indicates the desiredoperation of the motor. The command signal may be a desired torque,speed, or position at which the motor is to operate. The torque, speed,or position of the motor are controlled by varying the amplitude andfrequency of the AC voltage applied to the stator. An inverter sectionis provided between the DC bus and the output of the motor drive togenerate the controlled AC voltage. The inverter section includes powerelectronic switching devices, such as IGBTs, MOSFETs, thyristors, orSCRs, and a reverse conduction power electronic device connected inparallel across the power electronic switching device. The motor isconnected to the output terminals of the motor drive, and the controllergenerates the switching signals to rapidly switch the switching devicesin the inverter on and off at a predetermined switching frequency and,thereby, to alternately connect or disconnect the DC bus to the outputterminals and, in turn, to the motor. By varying the duration duringeach switching period for which the output terminal of the motor driveis connected to the DC voltage, the magnitude of the output voltage isvaried. The motor controller utilizes modulation techniques such aspulse width modulation (PWM) to control the switching and to synthesizewaveforms having desired amplitudes and frequencies.

As is also known, the output voltage waveform generated by modulationtechniques is a series of square waves, where the magnitude may be zerovolts, a maximum positive voltage, or a maximum negative voltage. Theduration for which the voltage is connected to zero voltage, the maximumpositive voltage, or the maximum negative voltage within any switchingperiod results in an average value of the output voltage for thatswitching period. The output voltage is regulated to provide a waveformhaving a fundamental component corresponding to a desired AC outputvoltage. The modulation typically occurs at frequencies ranging from thehundreds of hertz to tens of kilohertz while the desired fundamentalfrequency of the AC output voltage is typically in the tens to hundredsof hertz. While the AC output voltage contains a fundamental component,the modulation introduces components at the switching frequency andharmonics thereof. These components may be conducted, for example, via acable connected between the motor drive and a motor to be controlled bythe motor drive or radiated from the motor drive generating conducted orradiated electromagnetic interference (EMI) for other electroniccomponents located near the motor drive, cabling, or motor.

As is also known to those skilled in the state of the art, thenon-sinusoidal PWM output voltage includes high dv/dt voltagetransitions which generate possible motor insulation failure and systemground current issues. First, high dv/dt transitions cause unevenvoltage distributions across motor windings. A high percentage of the DCbus voltage is distributed across the first few incoming turns of thestator coil and the corresponding winding insulation, which may causeinsulation failure. Second, high dv/dt transitions may cause doubling ofthe DC bus voltage magnitude to be observed on the output cable and atthe motor terminals. The doubling of the DC bus voltage results fromstanding waves or reflected voltages present on the cable as a result ofimpedance mismatch as defined by well-known pulsed transmission linetheory, leading to insulation failure. Third, high dv/dt transitionsfrom conducted emissions along the cable and into the motor may betransmitted via stray ground capacitance and lead to uncontrolledexternal paths of ground noise current spikes that may adversely affectnearby sensitive equipment. Higher switching frequencies increase thedv/dt transitions and increase the magnitude of the ground noise currentspikes.

Thus, it would be desirable to provide an improved motor drive topologythat outputs a sinusoidal waveform which has a low dv/dt transition.

It would also be desirable to provide an improved motor drive topologythat includes integrated EMI filtering to contain conducted or radiatedEMI content resulting from modulation techniques within the motor drive.

BRIEF DESCRIPTION

The subject matter disclosed herein describes a motor drive that outputsa sinusoidal waveform and eliminates EMI conducted or radiated from themotor drive. The motor drive utilizes power switching devices operableat high switching frequencies. The switching devices may be operated,for example, between twenty kilohertz (20 kHz) and one megahertz (1MHz). As a result of the high frequency switching, the conducted andradiated emissions generated are similarly in this high frequency rangeor multiples thereof. As previously indicated, the higher switchingfrequency results in a greater dv/dt transition and an increasedmagnitude of these conducted emissions. However, the higher frequencyemissions can be attenuated by filtering components having a smallerphysical size than emissions at a lower frequency. As a result, thepresent inventors have been able to incorporate the filtering componentswithin the motor drive.

The motor drive includes multiple filters and shielding to containconducted and radiated EMI content resulting from modulation techniqueswithin the motor drive. A first filter is included at the output of themotor drive which has a bandwidth selected to attenuate voltagecomponents at the output at the switching frequency or multiples thereofsuch that the output voltage waveform is generally sinusoidal.Additional filtering is included within the motor drive to establish acirculation path for common mode currents within the motor drive.Finally, an electromagnetic interference (EMI) shield is providedadjacent to those components within the motor drive that may experiencevoltage or current waveforms at the switching frequency or multiplesthereof. The EMI shield is made of a conductive material such thatradiated emissions establish eddy currents within the EMI shield ratherthan passing through the shield into the environment. The result is amotor drive with a sinusoidal voltage output that satisfieselectromagnetic compatibility (EMC) requirements without requiringadditional chokes, filters, or shielding external to the motor drive.

According to one embodiment of the invention, a motor drive includes aninput configured to receive an AC input voltage and a converter sectionhaving an input and an output. The input to the converter section isconfigured to receive the AC input voltage, and the output from theconverter section is configured to output a DC voltage. The convertersection is operative to convert the AC input voltage to the DC voltage.The motor drive also includes an input filter operatively connectedbetween the input of the motor drive and the input of the convertersection, where the input filter includes a common connection. The motordrive has a DC bus, a DC bus capacitance, and an inverter section. TheDC bus has a positive rail connected to a first terminal of the outputof the converter section and a negative rail connected to a secondterminal of the output of the converter section. The DC bus capacitanceis connected between the positive rail and the negative rail of the DCbus at the output of the converter section. The inverter section has aninput and an output. The input of the inverter section is configured toreceive the DC voltage from the DC bus, and the output from the invertersection is configured to output an AC output voltage. The invertersection is operative to covert the DC voltage to the AC output voltage.A high frequency capacitance is connected between the positive rail andthe negative rail of the DC bus at the input of the inverter section,and an output from the motor drive is configured to supply the AC outputvoltage to a motor operatively connected to the motor drive. The motordrive also includes an output filter operatively connected between theoutput of the inverter section and the output of the motor drive. Theoutput filter is connected to the common connection and common modecurrents present in the motor drive circulate within the motor drive viathe common connection between the input filter and the output filter.

According to another embodiment of the invention, a motor drive includesan input configured to receive an AC input voltage and a convertersection having an input and an output. The input to the convertersection is configured to receive the AC input voltage and the outputfrom the converter section is configured to output a DC voltage. Theconverter section is operative to convert the AC input voltage to the DCvoltage. The motor drive also includes a DC bus, a DC bus capacitance,and an inverter section. The DC bus has a positive rail connected to afirst terminal of the output of the converter section and a negativerail connected to a second terminal of the output of the convertersection. The DC bus capacitance is connected between the positive railand the negative rail of the DC bus at the output of the convertersection. The inverter section has an input and an output. The input ofthe inverter section is configured to receive the DC voltage from the DCbus and the output of the inverter section is configured to output an ACoutput voltage. The inverter section is operative to covert the DCvoltage to the AC output voltage. A high frequency capacitance isconnected between the positive rail and the negative rail of the DC busat the input of the inverter section, and an output of the motor driveis configured to supply the AC output voltage to a motor operativelyconnected to the motor drive. The motor drive also includes a firstfilter and a second filter. The first filter is operatively connectedbetween the output of the converter section and the high frequencycapacitance, where the first filter includes a common connection. Thesecond filter is operatively connected between the output of theinverter section and the output of the motor drive. The second filter isconnected to the common connection, and common mode currents present inthe motor drive circulate within the motor drive via the commonconnection between the first filter and the second filter.

According to still another embodiment of the invention, a motor driveincludes an input, a converter section, an inverter section, and anoutput. The input is configured to receive an AC input voltage, and theconverter section is configured to convert the AC input voltage to a DCbus voltage The inverter section is configured to convert the DC busvoltage to an AC output voltage using a modulation technique, where themodulation technique executes at a switching frequency, and the outputis configured to supply an AC output voltage. A DC bus is operative toconduct the DC bus voltage between the converter section and theinverter section, and a sinusoidal output filter is operative toattenuate harmonic content on the AC output voltage at frequencies equalto or greater than the switching frequency. A first portion of anelectromagnetic compatibility (EMC) filter operatively is connectedbetween the input of the motor drive and the converter section, and asecond portion of the EMC filter is operatively connected between theinverter section and the output of the motor drive. Both the first andsecond portions of the EMC filter are connected to a common connection,where common mode currents present in the motor drive circulate withinthe motor drive via the common connection between the first and secondportions of the EMC filter.

These and other advantages and features of the invention will becomeapparent to those skilled in the art from the detailed description andthe accompanying drawings. It should be understood, however, that thedetailed description and accompanying drawings, while indicatingpreferred embodiments of the present invention, are given by way ofillustration and not of limitation. Many changes and modifications maybe made within the scope of the present invention without departing fromthe spirit thereof, and the invention includes all such modifications.

BRIEF DESCRIPTION OF THE DRAWINGS

Various exemplary embodiments of the subject matter disclosed herein areillustrated in the accompanying drawings in which like referencenumerals represent like parts throughout, and in which:

FIG. 1 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to one embodiment of the invention;

FIG. 2 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 3 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 4 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 5 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 6 is a schematic representation of a motor drive with integratedFMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 7 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 8 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 9 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 10 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 11 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 12 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 13 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 14 is a schematic representation of a motor drive with integratedEMC filtering configured to provide a sinusoidal voltage outputaccording to another embodiment of the invention;

FIG. 15 is a schematic representation of a passive converter section foruse in the motor drive of any one of FIGS. 1 to 14;

FIG. 16 is a schematic representation of an active converter section foruse in the motor drive of any one of FIGS. 1 to 14;

FIG. 17 is a top view of a magnetic component integrated into a printedcircuit board (PCB) for use as an inductive component in one of thefilters according to one embodiment of the invention;

FIG. 18 is a top plan view of the PCB for the magnetic component of FIG.17;

FIG. 19 is an exploded view of the PCB for the magnetic component ofFIG. 17;

FIG. 20 is a sectional view of one embodiment of the PCB for themagnetic component of FIG. 17;

FIG. 21 is a perspective view of a motor drive with an EMI shieldextending over a portion of the internal circuit board;

FIG. 22 is a perspective view of a housing for the motor drive of FIG.21 with the EMI shield mounted to an interior surface of the housing;

FIG. 23 is a top plan view of the internal circuit board with a blockdiagram representation of an EMI shield covering a portion of thecircuit board;

FIG. 24 is a schematic representation of the L-C filter of FIG. 1 withthe capacitors connected in a delta configuration;

FIG. 25 is a schematic representation of a distributed motor drivesystem with integrated EMC filtering configured to provide a sinusoidalvoltage output from each inverter according to another embodiment of theinvention; and

FIG. 26 is a schematic representation of another distributed motor drivesystem with integrated EMC filtering configured to provide a sinusoidalvoltage output from each inverter according to another embodiment of theinvention.

In describing the various embodiments of the invention which areillustrated in the drawings, specific terminology will be resorted tofor the sake of clarity. However, it is not intended that the inventionbe limited to the specific terms so selected and it is understood thateach specific term includes all technical equivalents which operate in asimilar manner to accomplish a similar purpose. For example, the word“connected,” “attached,” or terms similar thereto are often used. Theyare not limited to direct connection but include connection throughother elements where such connection is recognized as being equivalentby those skilled in the art.

DETAILED DESCRIPTION

The various features and advantageous details of the subject matterdisclosed herein are explained more fully with reference to thenon-limiting embodiments described in detail in the followingdescription.

Turning initially to FIG. 1, a first embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

After the input 22 of the motor drive 20, a first filter 24 and a secondfilter 30 are connected in series between the input 22 and a convertersection 40 of the motor drive. The first filter 24 includes a capacitor26 connected between each phase of the AC input voltage and a commonconnection point 25 for the first filter. For the three-phase AC inputvoltage 12 illustrated, the first filter 24 includes three capacitors 26each connected between one phase of the input voltage and the commonconnection point 25. Optionally, a fourth capacitor 28 may also beprovided. The fourth capacitor 28 is connected between the commonconnection point 25 of the first filter 24 and a common connection 15for the motor drive 20. The common connection 15 shown in FIG. 1 is aground connection. As will be discussed in more detail below, connectingmultiple filters to the common connection 15 will allow common modecurrents 180 (shown in FIG. 2) to circulate within the motor drive 20.The second filter 30 includes an AC common mode inductor 32, alsoreferred to as an AC common mode choke, connected in series with the ACinput voltage 12. The AC common mode inductor 32 includes a winding foreach phase of the AC input voltage which may be wrapped around a singlecore or, optionally, windings wrapped around separate cores. Thewindings for the common mode inductor 32 are connected between the firstfilter and an input 42 for the converter section 40.

The converter section 40 may include any electronic device suitable forpassive or active rectification as is understood in the art. Withreference also to FIG. 15, the illustrated converter section 40A is apassive converter and includes a set of diodes 44 forming a diodebridge. The converter section 40 receives the AC voltage at an input 42,rectifies the three-phase AC voltage to a DC voltage, and provides theDC voltage to a DC bus 50 at an output of the converter section. Withreference also to FIG. 16, the illustrated converter section 40B is anactive converter. An active converter 40B includes switching devicesincluding, but not limited to, thyristors, silicon-controlled rectifiers(SCRs), or transistors, such as IGBTs or MOSFETs, to convert the voltageat the input 42 from AC to a DC voltage for the DC bus 50. According tothe illustrated embodiment, a pair of transistors 46 is connectedbetween each phase of the input voltage and the DC bus 50. A firsttransistor in the pair is connected between the input voltage and apositive rail 52 of the DC bus 50, and a second transistor in the pairis connected between the input voltage and a negative rail 54 of the DCbus 50. Diodes 48 may be connected in a reverse parallel manner acrosseach transistor 46. A driver circuit 41 generates switching signals 45to control operation of each transistor 46. The active converter 40B mayboth convert the AC voltage to a DC voltage as well as allow forbidirectional current flow between the input 42 of the converter section40B and the DC bus 50. The DC bus 50 is connected to the output of theconverter section, and the DC voltage output by the converter is presentbetween the positive rail 52 and the negative rail 54 of the DC bus 50.

A DC bus capacitor 55 is connected between the positive and negativerails, 52 and 54, to reduce the magnitude of the ripple voltageresulting from converting the AC voltage to a DC voltage. It isunderstood that the DC bus capacitor 55 may be a single capacitor ormultiple capacitors connected in parallel, in series, or a combinationthereof. The magnitude of the DC voltage between the negative andpositive rails, 54 and 52, is generally equal to the magnitude of thepeak of the AC input voltage.

As shown in FIG. 1, a DC bus charge circuit 57 may be connected on theDC bus 50. In the illustrated embodiment, the DC bus charge circuit 57is connected between the output of the converter section 40 and the DCbus capacitor 55. Initially, a switch 56 is in a normally open state,establishing a conduction path from the output of the converter section40 to the positive rail 52 via a charge resistor 58. The charge resistor58, in combination with the DC bus capacitor 55 establishes a chargingtime constant, as is understood in the art, to allow the DC voltage onthe DC bus 50 to Charge from zero volts DC at power up to a voltagelevel approximately equal to the full DC bus voltage resulting fromrectifying the AC input voltage. When the DC voltage level reaches apreset charged level, the switch 56 is closed, bypassing the chargeresistor 58 and allowing current to flow directly from the convertersection 40 onto the DC bus 50,

The DC bus 50 is connected in series between the converter section 40and an inverter section 100. Also illustrated either in series with orparallel to the DC bus 50 between the converter section 40 and theinverter section 100 are a third filter 60, fourth filter 70, fifthfilter 80, and sixth filter 90. The third filter 60 includes a first DCcommon mode inductor 62, also referred to as a DC common choke,connected in series with the DC bus 50. Conductors for both the positiverail 52 and the negative rail 54 are wrapped around a common core andconnected in series with each rail. The fifth filter 80 similarlyincludes a second DC common mode inductor 82, also referred to as a DCcommon choke, connected in series with the DC bus 50. Conductors forboth the positive rail 52 and the negative rail 54 are wrapped around acommon core and connected in series with each rail. Optionally, a singlefilter may be provided with just one DC common mode inductor sizedaccording to application requirements. In still other embodiments, no DCcommon mode inductor may be required as will be discussed in more detailbelow.

According to the embodiment illustrated in FIG. 1, the fourth filter 70is positioned between the third filter 60 and the fifth filter 80 alongthe DC bus 50. The fourth filter 70 includes a first DC bus filtercapacitor 72 and a second DC bus filter capacitor 74. A first terminalof the first DC bus filter capacitor 72 is connected to the positiverail 52 and a second terminal of the first DC bus filter capacitor 72 isconnected to a common point 76 for the filter. A first terminal of thesecond DC bus filter capacitor 74 is connected to the negative rail 54and a second terminal of the second DC bus filter capacitor 74 isconnected to the common point 76 for the filter. The two DC bus filtercapacitors 72, 74 are preferably equal in capacitance and create abalanced voltage potential across each capacitor. The common point 76 isconnected to the common connection 15 of the motor drive 20,establishing one additional flow path for common mode currents tocirculate within the motor drive 20.

The sixth filter 90 includes a high frequency capacitance 92 connectedbetween the positive rail 52 and the negative rail 54 of the DC bus 50.It is understood that the high frequency capacitance 92 may be a singlecapacitor or multiple capacitors connected in parallel, in series, or acombination thereof. The high frequency capacitance 92 is connected atthe input of the inverter section 100 and is used to reduce themagnitude of the ripple voltage present on the DC bus 50 as a result ofthe high frequency switching in the inverter section to convert the DCvoltage back to an AC voltage. The output of the multi-stage filtersection is a filtered DC bus and is shown as a positive filtered DC busrail 102 and a negative filtered DC bus rail 104.

The inverter section 100 consists of switching elements, such astransistors, thyristors, or SCRs as is known in the art. The illustratedinverter section 100 includes a power metal-oxide-semiconductorfield-effect transistor (MOSFET) 106 and a reverse connected device 108,which may be a free-wheeling diode or a MOSFET's inherent body diode,connected in pairs between the filtered positive rail 102 and each phaseof the output voltage (110 U, 110V, 110 W) as well as between thefiltered negative rail 104 and each phase of the output voltage. Each ofthe transistors 106 receives switching signals 116 to selectively enablethe transistors 106 and to convert the DC voltage from the DC bus 50into a controlled three phase output voltage to the motor 10. Whenenabled, each transistor 106 connects the respective rail 102, 104 ofthe DC bus to one output phase 110, which is, in turn, connected betweenthe inverter section 100 and the output terminal 160.

According to the embodiment illustrated in FIG. 1, a processor 112 and adriver circuit 114 may include and manage execution of modules used tocontrol operation of the motor drive 20. The illustrated embodiment isnot intended to be limiting and it is understood that various featuresof each module may be executed by another module and/or variouscombinations of other modules may be included in the processor 112without deviating from the scope of the invention. The modules may bestored programs executed on one or more processors, logic circuits, or acombination thereof. The processor 112 may be implemented, for example,in a microprocessor, application specific integrated circuit (ASIC),field programmable gate array (FPGA), or other such customizable device.The motor drive 20 also includes a memory device 115 in communicationwith the processor 112. The memory device 115 may include transitorymemory, non-transitory memory or a combination thereof. The memorydevice 115 may be configured to store data and programs, which include aseries of instructions executable by the processor 112. It iscontemplated that the memory device 115 may be a single device, multipledevices, or incorporated, for example, as a portion of another devicesuch as an application specific integrated circuit (ASIC). The processor112 is in communication with the memory 115 to read the instructions anddata as required to control operation of the motor drive 20.

According to one embodiment of the invention, the processor 112 receivesa reference signal identifying desired operation of the motor 10connected to the motor drive 20. The reference signal may be, forexample, a torque reference (T*), a speed reference (ω*), or a positionreference (θ*). The processor 112 also receives feedback signalsindicating the current operation of the motor drive 20. The motor drive20 may include a voltage sensor and/or a current sensor operativelyconnected to the DC bus 50 and generating a feedback signalcorresponding to the magnitude of voltage and/or current present on theDC bus. The motor drive 20 may also include one or more voltage sensorsand/or current sensors 152 on each phase of the AC output voltagegenerating a feedback signal 154 corresponding to the magnitude ofvoltage and/or current present at the output 160 of the motor drive 20.

The processor 112 utilizes the feedback signals and the reference signalto control operation of the inverter section 100 to generate an outputvoltage having a desired magnitude and frequency for the motor 10. Theprocessor 112 may generate a desired output voltage signal to a drivermodule 114. The driver module 114, in turn, generates the switchingsignals 116, for example, by pulse width modulation (PWM) or by othermodulation techniques. The switching signals 116 subsequentlyenable/disable the transistors 106 to provide the desired output voltageto the motor 10, which, in turn, results in the desired operation of themotor 10.

Between the inverter section 100 and the output terminal 160 areillustrated still additional filter sections either in series with orparallel to each phase of the AC output voltage. As illustrated, themotor drive 20 includes a seventh filter 120, an eighth filter 130, anda ninth filter 140. Each of the seventh, eighth, and ninth filters serveas output filters for the motor drive 20. The seventh filter 120includes an inductor 122 and a capacitor 124 for each phase of the ACoutput voltage. Each inductor 122 is connected in series with one phaseof the output voltage (110 U, 110V, 110 W) at the output of the invertersection 100. Capacitors 124 are then connected after the inductors 122and between each phase of the AC output voltage and a common connectionpoint 126 for the seventh filter in a wye configuration. For thethree-phase AC output voltage illustrated, the seventh filter 120includes three capacitors 124 each connected between one phase of theoutput voltage and the common connection point 126. Alternately, thecapacitors 124 may be connected in a delta configuration as shown inFIG. 24. Optionally, a fourth capacitor 128 may also be provided. Thefourth capacitor 128 is connected between the common connection point126 of the seventh filter 120 and the common connection 15 for the motordrive 20.

The eighth filter 130 is connected in series with the output of theseventh filter on each phase of the AC output voltage (110 U, 110V, 110W). The eight filter includes an AC common mode inductor 132, alsoreferred to as an AC common mode choke. The AC common mode inductor 132includes a winding for each phase of the AC output voltage which may bewrapped around a single core or, optionally, include windings wrappedaround separate cores.

The ninth filter 140 includes three capacitors 142 each connectedbetween one phase of the AC output voltage and a common connection point144 for the ninth filter. The common connection point 144 of the ninthfilter 140 is connected to the common connection 15 for the motor drive20. As previously indicated, connecting the common connection point 126,144 of the seventh filter 120 or the ninth filter 140, respectively, tothe common connection 15 will allow common mode currents to circulatewithin the motor drive 20. It is contemplated that only a portion of thefilters (i.e., seventh, eighth, or ninth) are required in a particularembodiment to provide the necessary output filtering for the motor drive20.

A current sense module 150 is provided after the output filtering. Thecurrent sense module 150 includes a current sensor 152 on each phase ofthe AC output voltage. Each current sensor 152 generates a currentfeedback signal 154 corresponding to the current present at the output160 of the motor drive for each phase of the AC output.

The motor drive embodiment, as illustrated in FIG. 1 and describedabove, is not intended to be limiting. The described embodiment includesnumerous filters of which various combinations and/or portions of thefilters may be utilized to achieve a sinusoidal voltage output waveformwhile maintaining EMC compatibility. Satisfactory performance may beachieved with different combinations of the filters or with just aportion of the above-described filters. Although not intended to beexhaustive, several of the different embodiments will be describedbelow.

Turning next to FIG. 2, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 2 includes the first filter 24and the second filter 30 connected in series between the input 22 andthe converter section 40 of the motor drive. The converter section 40may be a passive converter section 40A or an active converter section40B as discussed above. The DC bus charge circuit 57 is connected at anoutput of the converter section 40 and between the converter section andthe DC bus capacitor 55. The motor drive further includes the thirdfilter 60, the fourth filter 70, the fifth filter 80, and the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120, eighth filter 130, and ninth filter 140 are connected inseries between the output of the inverter section 100 and the currentsensing segment 150 of the motor drive 20. The seventh filter 120includes an inductor 122 and a capacitor 124 for each phase of the ACoutput voltage. Each inductor 122 is connected in series with one phaseof the output voltage (110 U, 110V, 110 W) at the output of the invertersection 100. Capacitors 124 are then connected after the inductors 122and between each phase of the AC output voltage and a common connectionpoint 126 for the seventh filter in a wye configuration. In thisembodiment, the optional fourth capacitor 128, discussed above withrespect to FIG. 1, is not included.

Turning next to FIG. 3, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 3 includes the first filter 24and the second filter 30 connected in series between the input 22 andthe converter section 40 of the motor drive. The converter section 40may be a passive converter section 40A or an active converter section40B as discussed above. The DC bus charge circuit 57 is connected at anoutput of the converter section 40 and between the converter section andthe DC bus capacitor 55. The motor drive further includes the thirdfilter 60, the fourth filter 70, the fifth filter 80, and the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120 and ninth filter 140 are connected in series between theoutput of the inverter section 100 and the current sensing segment 150of the motor drive 20. The seventh filter 120 includes an inductor 122and a capacitor 124 for each phase of the AC output voltage. Eachinductor 122 is connected in series with one phase of the output voltage(110 U, 110V, 110 W) at the output of the inverter section 100.Capacitors 124 are then connected after the inductors 122 and betweeneach phase of the AC output voltage and a common connection point 126for the seventh filter in a wye configuration. In this embodiment, theoptional fourth capacitor 128, discussed above with respect to FIG. 1,is not included.

Turning next to FIG. 4, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 4 includes the first filter 24and the second filter 30 connected in series between the input 22 andthe converter section 40 of the motor drive. The converter section 40may be a passive converter section 40A or an active converter section40B as discussed above. The DC bus charge circuit 57 is connected at anoutput of the converter section 40 and between the converter section andthe DC bus capacitor 55. The motor drive further includes the fourthfilter 70, the fifth filter 80, and the sixth filter 90 connected inseries between the DC bus capacitor 55 and the inverter section 100. Theprocessor 112 and driver circuit 114 control operation of the invertersection 100 as discussed above. The seventh filter 120 and ninth filter140 are connected in series between the output of the inverter section100 and the current sensing segment 150 of the motor drive 20. Theseventh filter 120 includes an inductor 122 and a capacitor 124 for eachphase of the AC output voltage. Each inductor 122 is connected in serieswith one phase of the output voltage (110 U, 110V, 110 W) at the outputof the inverter section 100. Capacitors 124 are then connected after theinductors 122 and between each phase of the AC output voltage and acommon connection point 126 for the seventh filter in a wereconfiguration. In this embodiment, the optional fourth capacitor 128,discussed above with respect to FIG. 1, is not included.

Turning next to FIG. 5, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 5 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the third filter 60, the fourthfilter 70, the fifth filter 80, and the sixth filter 90 connected inseries between the DC bus capacitor 55 and the inverter section 100. Theprocessor 112 and driver circuit 114 control operation of the invertersection 100 as discussed above. The seventh filter 120 and ninth filter140 are connected in series between the output of the inverter section100 and the current sensing segment 150 of the motor drive 20. Theseventh filter 120 includes an inductor 122 and a capacitor 124 for eachphase of the AC output voltage. Each inductor 122 is connected in serieswith one phase of the output voltage (110 U, 110V, 110 W) at the outputof the inverter section 100. Capacitors 124 are then connected after theinductors 122 and between each phase of the AC output voltage and acommon connection point 126 for the seventh filter in a wyeconfiguration. In this embodiment, the optional fourth capacitor 128,discussed above with respect to FIG. 1, is not included.

Turning next to FIG. 6, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 6 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the fourth filter 70, the fifthfilter 80, and the sixth filter 90 connected in series between the DCbus capacitor 55 and the inverter section 100. The processor 112 anddriver circuit 114 control operation of the inverter section 100 asdiscussed above. The seventh filter 120 and ninth filter 140 areconnected in series between the output of the inverter section 100 andthe current sensing segment 150 of the motor drive 20. The seventhfilter 120 includes an inductor 122 and a capacitor 124 for each phaseof the AC output voltage. Each inductor 122 is connected in series withone phase of the output voltage (110 U, 110V, 110 W) at the output ofthe inverter section 100. Capacitors 124 are then connected after theinductors 122 and between each phase of the AC output voltage and acommon connection point 126 for the seventh filter in a wyeconfiguration. In this embodiment, the optional fourth capacitor 128,discussed above with respect to FIG. 1, is not included.

Turning next to FIG. 7, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 7 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the fifth filter 80 and the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120 and ninth filter 140 are connected in series between theoutput of the inverter section 100 and the current sensing segment 150of the motor drive 20. The seventh filter 120 includes an inductor 122and a capacitor 124 for each phase of the AC output voltage. Eachinductor 122 is connected in series with one phase of the output voltage(110 U, 110V, 110 W) at the output of the inverter section 100.Capacitors 124 are then connected after the inductors 122 and betweeneach phase of the AC output voltage and a common connection point 126for the seventh filter in a wye configuration. In this embodiment, theoptional fourth capacitor 128, discussed above with respect to FIG. 1,is not included.

Turning next to FIG. 8, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 8 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The first filter 24 includes a capacitor 26 connectedbetween each phase of the AC input voltage and a common connection point25 for the first filter. In this embodiment, the optional fourthcapacitor 28, discussed above with respect to FIG. 1, is not included.The converter section 40 may be a passive converter section 40A or anactive converter section 40B as discussed above. The DC bus chargecircuit 57 is connected at an output of the converter section 40 andbetween the converter section and the DC bus capacitor 55. The motordrive further includes the fourth filter 70, the fifth filter 80, andthe sixth filter 90 connected in series between the DC bus capacitor 55and the inverter section 100. The processor 112 and driver circuit 114control operation of the inverter section 100 as discussed above. Theseventh filter 120 and ninth filter 140 are connected in series betweenthe output of the inverter section 100 and the current sensing segment150 of the motor drive 20. The seventh filter 120 includes an inductor122 and a capacitor 124 for each phase of the AC output voltage. Eachinductor 122 is connected in series with one phase of the output voltage(110 U, 110V, 110 W) at the output of the inverter section 100.Capacitors 124 are then connected after the inductors 122 and betweeneach phase of the AC output voltage and a common connection point 126for the seventh filter in a wye configuration. In this embodiment, theoptional fourth capacitor 128, discussed above with respect to FIG. 1,is not included.

Turning next to FIG. 9, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 9 includes the first filter 24and the second filter 30 connected in series between the input 22 andthe converter section 40 of the motor drive. The converter section 40may be a passive converter section 40A or an active converter section40B as discussed above. The DC bus charge circuit 57 is connected at anoutput of the converter section 40 and between the converter section andthe DC bus capacitor 55. The motor drive further includes the thirdfilter 60, the fourth filter 70, the fifth filter 80, and the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120 is connected in series between the output of the invertersection 100 and the current sensing segment 150 of the motor drive 20.

Turning next to FIG. 10, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 10 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the third filter 60, the fourthfilter 70, the fifth filter 80, and the sixth filter 90 connected inseries between the DC bus capacitor 55 and the inverter section 100. Theprocessor 112 and driver circuit 114 control operation of the invertersection 100 as discussed above. The seventh filter 120 is connected inseries between the output of the inverter section 100 and the currentsensing segment 150 of the motor drive 20.

Turning next to FIG. 11, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 11 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the fourth filter 70, the fifthfilter 80, and the sixth filter 90 connected in series between the DCbus capacitor 55 and the inverter section 100. The processor 112 anddriver circuit 114 control operation of the inverter section 100 asdiscussed above. The seventh filter 120 is connected in series betweenthe output of the inverter section 100 and the current sensing segment150 of the motor drive 20.

Turning next to FIG. 12, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 12 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The first filter 24 includes a capacitor 26 connectedbetween each phase of the AC input voltage and a common connection point25 for the first filter. In this embodiment, the optional fourthcapacitor 28, discussed above with respect to FIG. 1, is not included.The converter section 40 may be a passive converter section 40A or anactive converter section 40B as discussed above. The DC bus chargecircuit 57 is connected at an output of the converter section 40 andbetween the converter section and the DC bus capacitor 55. The motordrive further includes the fourth filter 70, the fifth filter 80 and thesixth filter 90 connected in series between the DC bus capacitor 55 andthe inverter section 100. The processor 112 and driver circuit 114control operation of the inverter section 100 as discussed above. Theseventh filter 120 is connected in series between the output of theinverter section 100 and the current sensing segment 150 of the motordrive 20.

Turning next to FIG. 13, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 13 includes the first filter 24connected in series between the input 22 and the converter section 40 ofthe motor drive. The converter section 40 may be a passive convertersection 40A or an active converter section 40B as discussed above. TheDC bus charge circuit 57 is connected at an output of the convertersection 40 and between the converter section and the DC bus capacitor55. The motor drive further includes the fifth filter 80 and the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120 is connected in series between the output of the invertersection 100 and the current sensing segment 150 of the motor drive 20.

Turning next to FIG. 14, another embodiment of a motor drive 20incorporating EMI filtering and producing a sinusoidal voltage output isillustrated. An AC voltage 12 is provided at an input 22 to the motordrive 20. According to the illustrated embodiment, the AC voltage 12 isa three-phase AC input voltage. The motor drive supplies a sinusoidaloutput voltage from an output 160 of the motor drive to a motor 10operatively connected to the motor drive 20 via a cable 14. The outputvoltage is a three-phase AC output voltage with individual conductorsshown extending between the motor 10 and drive 20 for each phase as wellas for a ground conductor. It is understood that the illustratedconductors may be combined within a cable 14, run as individualconductors, or a combination thereof according to the applicationrequirements.

The motor drive 20 illustrated in FIG. 14 includes the first filter 24and the second filter 30 connected in series between the input 22 andthe converter section 40 of the motor drive. The converter section 40may be a passive converter section 40A or an active converter section40B as discussed above. The DC bus charge circuit 57 is connected at anoutput of the converter section 40 and between the converter section andthe DC bus capacitor 55. The motor drive further includes the sixthfilter 90 connected in series between the DC bus capacitor 55 and theinverter section 100. The processor 112 and driver circuit 114 controloperation of the inverter section 100 as discussed above. The seventhfilter 120 is connected in series between the output of the invertersection 100 and the current sensing segment 150 of the motor drive 20.

Turning next to FIGS. 17-19, one embodiment of an inductor, or set ofinductors for a multi-phase voltage, integrated into a PCB for use inone or more of the filters discussed above is illustrated. Integratingthe magnetic components into a PCB is discussed in detail in aco-pending application, which is also owned by Applicant, the co-pendingapplication assigned U.S. Ser. No. 16/398,486 was filed Apr. 30, 2019 istitled System and Method for Reducing Power Losses for Magneticsintegrated in a Printed Circuit Board and is incorporated herein byreference in its entirety. The magnetic component shown in FIGS. 17-19includes a coil 250 integrated on a printed circuit board (PCB) 220 foruse within the motor drive 20. The PCB includes multiple layers 230 andtraces 252 on each layer are joined together to form a single coil 250or to form multiple coils on the magnetic component. The PCB furtherincludes at least one opening 224 in the PCB through which a corecomponent 282 may pass. The traces 252 forming the coils may be laid outto encircle the opening and the core material, such that the magneticcomponent is defined by the coils and the core material. The dimensionsof traces on a layer may be varied within the coil to reduce eddycurrents within the traces resulting from air-gap fringing flux. Theair-gap fringing flux is greatest proximate the opening in the PCB andat the air-gap in the core component. By making the width of individualtraces that are closest to the opening within the coil narrower thantraces that are further from the opening, the conductive material of thecoil located within the region of high air-gap fringing flux is reduced.As a result, the eddy currents induced within the coil due to theair-gap fringing flux is reduced. Optionally, the position of tracesbetween layers of the PCB are varied. The locations of individual tracesare selected such that the trace is located in a region having a lowermagnetic field component and, therefore, reducing coupling to leakagefluxes within the magnetic component. A floating conductive layer mayalso be positioned between the coil and the core material. The floatingconductive layer may be a conductive sheet or series of traces locatedon one layer of the PCB and where the conductive layer is not connectedto the coil. The conductive layer is preferably located near a surfaceof the PCB such that eddy currents and the resulting heat induced withinthe conductive layer are more readily dissipated out of the PCB.

With reference again to FIGS. 17-19, the PCB 220 is a multi-layer boardwhere a coil 250 is defined by multiple loops of circuit traces 252 onthe PCB. A first opening 224 extends through the PCB 220 which isconfigured to receive a center portion of a core 280. A pair of sideopenings 229 also extend through the PCB 220 with a first side opening229 positioned to one side of the first opening 224 and a second sideopening 229 positioned on the opposite side of the first opening 224. An“E-shaped” member 284 of the core 280 may be inserted into the openingswith a central portion 281 of the core 280 extending through the firstopening 224 and a pair of side members 283 of the core 280 extendingthrough the side openings 229. A second member of the core, such as an“I-shaped” member 282 of the core 280 may be positioned on the reverseside of the PCB 220. Clips 227 extending up through the side openings229 secure the two members of the core 280 together and positivelyretain the core 280 to the PCB 220. Optionally, an adhesive material maybe applied between contacting surfaces of the “E-shaped” and “I-shaped”members to secure the core members together.

With reference also to FIG. 20, an exemplary sectional view of such anE-I core configuration is illustrated. The E-shaped member 284 isillustrated on the lower surface and the I-shaped member 282 isillustrated on the upper surface. It is understood that terms such asupper and lower, left and right, front and back, and the like areintended to be relational with respect to a figure and are not intendedto be limiting. The illustrated magnetic component 210 may be rotatedaround a vertical axis, horizontal axis, or about any other axis ofrotation for installation within a power converter and the associatedcomponents will similarly be rotated. It is further contemplated thatvarious other configurations of the core 280 may be utilized. Forexample, other shapes including, but not limited to, U-shaped members,C-shaped members, R-shaped members, T-shaped members, D-shaped members,F-shaped members, and the like may be utilized according to theapplication requirements. Suitable openings may be cut through the PCB220 and a suitable arrangement of traces 252 on each layer 230 of thePCB 220 may be implemented to complement the corresponding members ofthe core 280.

The circuit traces 252 are distributed on the PCB 220 such that theyloop around the opening 224. Multiple loops may be formed on each layer230 of the PCB 220 where an inner trace 254 is closest to the opening224 and outer trace 258 is furthest from the opening 224. Variousnumbers of intermediate traces 256 may be defined between the innertrace 254 and the outer trace 258. Vias extending between layers of thePCB 220 may join coils on different layers to form a single coilspanning multiple layers 230. The illustrated embodiment illustrated inFIGS. 17-19 includes 4 loops on a layer for ease of illustration. It iscontemplated that various other numbers of loops may be utilizedaccording to the application requirements. Similarly, the illustratedembodiment includes eight layers on the PCB. A top layer 226 and abottom layer 228 each include solder pads to which wires or otherelectrical conductors may be connected. Six intermediate layers 230a-230 f are illustrated between the top and bottom layers, where each ofthe intermediate layers 230 a-230 f includes four loops. It iscontemplated that the PCB 220 may include various other numbers oflayers 230 according to the length of the traces and number of loopsdesired. The PCB 20 may include, for example, twenty layers or more. Thenumber, length, and cross-section of the traces defining loops on alayer 230 and further the number of layers 230 on which loops arepresent define an inductance for the magnetic component. The layout andselection of the number of loops and number of layers, therefore, areselected according to the filtering requirements of the application inwhich the magnetic component is integrated.

Turning next to FIGS. 21-23, the motor drive 20 includes a radiatedemissions shield 320. With reference first to FIG. 21, the motor drive20 includes a chassis 300 configured to be mounted within a controlcabinet. The chassis 300 includes a generally flat plate 301 to bemounted to a surface within the control cabinet. A mounting hole 302near one end of the plate 301 and a mounting slot 304 near the other endof the plate are configured to receive a fastener, such as a screw,through the hole or slot to secure the chassis to the surface of thecontrol cabinet. A primary PCB 330 within the motor drive 20 includeselectronic components for operation of the motor drive 20 mountedthereto. The electronic components are mounted to a front surface 332 ofthe primary PCB 330 and face inwards to the motor drive 20, while a rearsurface 334 of the primary PCB 330 faces outwards from the motor drive20.

In FIG. 21, a first embodiment of a radiated emissions shield 320 isillustrated mounted to the rear surface 334 of the primary PCB 330. Theradiated emissions shield 320 is a conductive surface which is operativeto absorb radio frequency (RF) energy emitted from the PCB 330 creatingeddy currents in the shield 320. The shield 320 is tied to a commonconnection, such as a ground connection, in order that currents inducedin the shield are carried to the ground connection. The radiatedemissions shield 320 may be, for example, a metal plate mounted bystandoffs to the rear surface 334 of the primary PCB 330. Optionally,the radiated emissions shield 320 may be a conductive coating, where aninsulative coating may first be applied to the rear surface 334 toprevent establishing conduction paths between traces, vias, and thelike, and the conductive coating is then applied over the insulativecoating to the rear surface 334 of the primary PCB 330.

In FIG. 22, a second embodiment of the radiated emissions shield 320 isillustrated mounted to an inside surface of a housing 310 for the motordrive 20. The housing 310 may mount over the chassis 300 shown in FIG.21 and position the radiated emissions shield 320 with respect to theprimary PCB 330. The shield 320 is tied to a common connection, such asa ground connection, in order that currents induced in the shield arecarried to the ground connection. The radiated emissions shield 320 maybe, for example, a metal plate mounted to the interior surface of thehousing 310. Optionally, the radiated emissions shield 320 may be aconductive coating applied to surface.

Turning next to FIG. 23, the orientation of the radiated emission shield320 with respect to the primary PCB 330 is illustrated. The radiatedemissions shield 320 is shown covering at least a portion of the primaryPCB 330. Electrical components located behind the shield 320 include,for example, the driver module 114, inverter section 100, seventh filter120, eighth filter 130, located at the output of the motor drive 20 and,in which, high frequency current and/or voltage components may bepresent as a result of the operation of the inverter section 100.Although illustrated as covering only a portion of the primary PCB 330.It is contemplated that the shield 320 may take other shapes and cover,for example, the entire primary PCB 330. In some embodiments of theinvention, it is also contemplated that the motor drive 20 may include afirst and a second radiated emission shield, where a first shield 320 islocated on one side of the primary PCB 330 and a second shield 320 islocated on the other side of the primary PCB 330.

In operation, the motor drive 20 is configured to generate a sinusoidaloutput voltage waveform to control operation of a motor 10 connected tothe motor drive. Switching devices in the inverter section 100 areselected which are suitable for high frequency switching. The switchingdevice may be, for example, field-effect transistors (FETs) made ofSilicon Carbide (SiC) MOSFET or Gallium Nitride (GaN FET) where theswitching frequencies may increase to tens or hundreds of kilohertz(e.g., 20 kHz-1 MHz) in contrast to traditional IGBTs which aretypically limited to upper switching frequencies in the range of 10kHz-20 kHz. The greater the frequency at which the power switchingdevices are able to be modulated, the lower the amplitude of theharmonic content present on the output of the motor drive. Thus,including switching devices suitable for switching in the tens tohundreds of kilohertz range reduces the magnitude of the harmoniccontent that requires filtering and similarly reduces the amount of heatgenerated in the magnetic component as a result of the power beingdissipated in that magnetic component.

Integration of a magnetic device, such as the inductors 122 in theseventh filter 120 at the output of the inverter section 100 in themotor drive 20 may attenuate or eliminate the harmonic content of theoutput voltage while allowing the desired fundamental component to beprovided at the output 160 to the motor 10. Each inductor 122 may beimplemented as one of the magnetic components 210 illustrated in FIGS.17-20. Implementing the inductor windings as traces 254 on the PCB 220and providing the magnetic cores 280 as shown allow three magneticcomponents 210 to be positioned next to each other in a stacked fashion(as shown in FIG. 23), reducing the surface are required on the primaryPCB 330.

As previously indicated, connecting multiple filters to the commonconnection 15 allows common mode currents 180 to circulate within themotor drive 20. As illustrated in FIGS. 2-14, various conduction pathsexist for the common mode currents to circulate from the outputfilter(s), through the common connection 15 to the input filter(s).Additionally, in some embodiments, multiple conduction paths existbetween the input filter(s), output filter(s), and/or an intermediatefilter(s), where the input filter is located before the convertersection 40, the intermediate filter is located between the convertersection 40 and the inverter section 120, and the output filter islocated after inverter section. Circulation of the common mode currentswithin the motor drive 20 eliminates the requirement of an externaloverall shield conductor surrounding the other conductors within theoutput cable 14.

Providing a sinusoidal output voltage waveform and eliminating theconducted emissions at the output 160 of the motor drive 20 providesseveral advantages to the motor 10 and motor drive 20 system.Electromagnetic noise seen on the motor cable 14 is significantlyreduced or eliminated. As is understood in the art, the electromagneticnoise may introduce ripple currents at the output 160 of the motor driveat the switching frequency or harmonics thereof. In traditional motordrives, these ripple currents may generate excessive acoustic noise orcause reflected waveforms on the motor cables 14 thereby limiting thelength of the cables 14. Certain applications may impose cable lengthrestrictions, for example, of ten to fifty meters (10-50 m).Additionally, the motor cables 14 are typically shielded cablesrequiring a shield conductor and/or a braided shield extending thelength of the cable and secure connections to ground at the end of thecable 14. By providing a sinusoidal output voltage and causing thereduced magnitude common mode currents to circulate within the motordrive 20, the shielding requirements on the motor cables 14 may beeliminated. Similarly, the maximum cable length restrictions resultingfrom harmonic content may be removed. Cable length restrictions duesolely to the voltages output at the fundamental frequency extend tomiles of cable length. Further, the elimination of the current ripple,in turn, eliminates torque ripple at the motor 10 resulting from thecurrent ripple. A purely sinusoidal output voltage as opposed to amodulated output voltage reduces stress on motor insulation and motorbearings as well, increasing the life of the motor 10 connected to themotor drive 20.

FIGS. 1-14, as discussed above, discuss a first embodiment of a motordrive topology that provides an improved sinewave output voltagewaveform and its associated benefit to motor operation. The disclosedmotor drive topology also provides improvements resulting fromintegrated differential mode and common mode filtering EMC filtering andradiated emission shielding for a single motor drive system. It iscontemplated that the disclosed motor drive topology may be connected toa common AC bus utility line and a separate motor drive 20 may beprovided to control each motor 10 in the system.

However, many controlled machines and processes find it advantageous toutilize a distributed motor drive topology. In a distributed motor drivetopology, individual inverter sections are connected to a common dc bus.In a common dc bus system, when a first motor, also referred to as anaxis, is motoring in steady state and a second axis is decelerating,generating excess regenerative energy which is supplied back onto the dcbus, the first axis can utilize that energy. This topology eliminatesthe need for DC brake resistor circuits for every axis to dissipateregenerative energy, resulting in reduction of energy cost, materialcost, system size, and system weight. Further, certain applications,such as a roll wind—rewind configuration, operate one axis continuouslyin a motoring mode and another axis continuously in a regenerative mode.The connection to the AC utility can be smaller since it only needs tobe rated to supply system energy losses, reducing cost of energysupplied by the AC utility. FIG. 25 and FIG. 26 show two possibleembodiments with a common dc bus and distributed inverter sectionconfiguration.

Turning first to FIG. 25, one embodiment for a Common DC bus topology isillustrated with two axes, or motors 10, controlled by distributed motordrives 220. Each distributed motor drive 220 is connected, via a commonDC bus 250 to a single rectifier module 240. However, it is contemplatedthat various numbers of axes may connected to the common DC bus 250without deviating from the scope of the invention. Each distributedmotor drive 220 includes a portion of the blocks discussed above withrespect to FIGS. 1-14 to provide an improved sinusoidal output voltagewaveshape at each set of output terminals 160 for each motor 10. Eachdistributed motor drive 220 further includes an integrated radiatedshield protection over the high frequency inverter section 150 on thePCB, as discussed previously. Each distributed motor drive 220illustrated in FIG. 25 includes the third filter 60, the fourth filter70, the fifth filter 80, and the sixth filter 90 connected in seriesbetween the common DC bus 250 and the inverter section 100. Theprocessor 112 and driver circuit 114 control operation of the invertersection 100 as discussed above. The seventh filter 120, eighth filter130, and ninth filter 140 are connected in series between the output ofthe inverter section 100 and the current sensing segment 150 of thedistributed motor drive 220. The fourth filter 70 and the sixth filteroperate to provide significant reduction in differential mode noisevoltage within each distributed motor drive 220. The fourth, fifth, andseventh through ninth filters attenuate and capture a majority of commonmode noise current emissions within each axis. Common mode chokes, suchas the inductors 132 in the eighth filter 130, attenuate the magnitudeof the common mode current, and capacitors connected to the commonconnection point 15 within the distributed motor drive 220 circulate andcontain a significant portion of the remaining common mode currentwithin each axis. The embodiment illustrated in FIG. 25 includes a thirdfilter 60 within each distributed motor drive 220. The DC common modechoke 62 in each filter reduces any remaining common mode currentflowing from the axis onto the shared DC bus 250 and prevents commoncurrents from one axis interacting with another axis.

The rectifier module 240 receives an AC voltage 12 at an input 22 to themodule. According to the illustrated embodiment, the AC voltage 12 is athree-phase AC input voltage. The rectifier module 240 illustrated inFIG. 25 includes the first filter 24 and the second filter 30 connectedin series between the input 22 and the converter section 40 of therectifier module 240. The converter section 40 may be a passiveconverter section 40A or an active converter section 40B as discussedabove. The DC bus charge circuit 57 is connected at an output of theconverter section 40 and between the converter section and the DC buscapacitor 55. The DC bus 50 from the rectifier module 240 is thenconnected to the common DC bus 250 at an output of the rectifier module240. The common Dc bus 250 is, in turn, configured to supply DC voltageto each of the distributed motor drive 220.

Turning next to FIG. 26, another embodiment for a common DC bus topologyis illustrated. This embodiment is configured in much the same manner asFIG. 25 except the third filter 60 and the corresponding DC common modechoke 62 is connected in the rectifier module 240 rather than beingrepeated in each distributed motor drive 200. This embodiment maydesirable if there is no appreciable interaction of common mode currentcirculating between different axis. It may further be desirable in anapplication in which one axis is configured to supply energy generatedin a regenerative operating mode to the common DC bus 250 and anotheraxis is configured to draw this regenerative energy from the common DCbus 250 for operation in a motoring mode. Although only two embodimentsof a common DC bus topology are illustrated, it is further contemplatedthat various other arrangements of the system illustrated in FIGS. 2-14may be employed in a common bus topology.

It should be understood that the invention is not limited in itsapplication to the details of construction and arrangements of thecomponents set forth herein. The invention is capable of otherembodiments and of being practiced or carried out in various ways.Variations and modifications of the foregoing are within the scope ofthe present invention. It also being understood that the inventiondisclosed and defined herein extends to all alternative combinations oftwo or more of the individual features mentioned or evident from thetext and/or drawings. All of these different combinations constitutevarious alternative aspects of the present invention. The embodimentsdescribed herein explain the best modes known for practicing theinvention and will enable others skilled in the art to utilize theinvention.

We claim:
 1. A motor drive, comprising: a DC bus having a positive railand a negative rail, the DC bus operative to maintain a DC voltagebetween the positive and negative rails; a DC bus capacitance connectedbetween the positive rail and the negative rail of the DC bus, whereinthe DC bus capacitance includes: a first DC bus capacitor connected at afirst terminal to the positive rail and connected at a second terminalto a common connection; and a second DC bus capacitor connected at afirst terminal to the negative rail and connected at a second terminalto the common connection; an inverter section having an input configuredto receive the DC voltage from the DC bus and an output configured tooutput an AC output voltage wherein the inverter section is operative tocovert the DC voltage to the AC output voltage; an output configured tosupply the AC output voltage to a motor operatively connected to themotor drive; and an output filter operatively connected between theoutput of the inverter section and the output of the motor drive,wherein the output filter is connected to the common connection andwherein common mode currents present in the motor drive circulate withinthe motor drive via the common connection between the output filter andthe DC bus capacitance.
 2. The motor drive of claim 1 wherein: the ACoutput voltage is a multi-phase AC output voltage; the output filterfurther comprises: a plurality of inductors wherein each inductor isconnected in series with one phase of the multi-phase AC output voltage,and a plurality of first capacitors, wherein each first capacitor isconnected between one phase of the multi-phase AC output voltage and afirst filter common connection point.
 3. The motor drive of claim 2further comprising a first common mode capacitor connected between thefirst filter common connection point and the common connection.
 4. Themotor drive of claim 3 further comprising: an input configured toreceive an AC input voltage; a converter section having an inputconfigured to receive the AC input voltage and an output configured tooutput the DC voltage to the DC bus wherein the converter section isoperative to convert the AC input voltage to the DC voltage; and aninput filter operatively connected between the input of the motor driveand the input of the converter section, wherein: the input filter isconnected to the common connection, the common mode currents present inthe motor drive circulate within the motor drive, in part, via thecommon connection between the output filter and the DC bus capacitance,and the common mode currents present in the motor drive circulate withinthe motor drive, in part, via the common connection between the outputfilter and the input filter.
 5. The motor drive of claim 4 wherein: theAC input voltage is a multi-phase AC input voltage, the input filterfurther comprises a plurality of second capacitors, and each secondcapacitor is connected between one phase of the multi-phase AC inputvoltage and a second filter common connection point.
 6. The motor driveof claim 5 further comprising a second common mode capacitor connectedbetween the second filter common connection point and the commonconnection.
 7. The motor drive of claim 6 further comprising a first DCcommon mode inductor connected in series on the DC bus between the DCbus capacitance and the inverter section.
 8. The motor drive of claim 7further comprising a second DC common mode inductor connected in serieson the DC bus between the converter section and the DC bus capacitance.9. The motor drive of claim 8 further comprising an AC common modeinductor connected in series on each phase of the multi-phase AC inputvoltage between the input filter and the converter section.
 10. Themotor drive of claim 4 further comprising a radiated emissions shield,wherein the radiated emissions shield extends over the input filter, theinverter section, and the output filter.
 11. A method of providing asinusoidal output voltage from a motor drive, the method comprising thesteps of: converting a DC voltage present on a DC bus to an AC outputvoltage with an inverter section of the motor drive, wherein: the DC busincludes a DC bus capacitance connected between a positive rail and anegative rail of the DC bus, the DC bus capacitance includes a first DCbus capacitor and a second DC bus capacitor, the first DC bus capacitoris connected at a first terminal to the positive rail and connected at asecond terminal to a common connection; and the second DC bus capacitoris connected at a first terminal to the negative rail and connected at asecond terminal to the common connection; filtering the AC outputvoltage within the motor drive with an output filter operativelyconnected between an output of the inverter section and an output of themotor drive, wherein the output filter is connected to the commonconnection; and circulating common mode currents within the motor drivevia the common connection between the output filter and the DC buscapacitance.
 12. The method of claim 12 wherein: the AC output voltageis a multi-phase AC output voltage, and the output filter includes: aplurality of inductors wherein each inductor is connected in series withone phase of the multi-phase AC output voltage, and a plurality of firstcapacitors, wherein each first capacitor is connected between one phaseof the multi-phase AC output voltage and a first filter commonconnection point.
 13. The method of claim 12 wherein the output filterfurther includes a first common mode capacitor connected between thefirst filter common connection point and the common connection.
 14. Themethod of claim 13 further comprising the steps of: receiving an ACinput voltage at an input of the motor drive; converting the AC inputvoltage to the DC voltage on the DC bus with a converter section; andfiltering the AC input voltage within the motor drive with an inputfilter operatively connected between the input of the motor drive and aninput of the converter section, wherein the input filter is connected tothe common connection; circulating common mode currents within the motordrive, in part, via the common connection between the output filter andthe DC bus capacitance; and circulating common mode currents within themotor drive, in part, via the common connection between the outputfilter and the input filter.
 15. The method of claim 14, wherein: the ACinput voltage is a multi-phase AC input voltage, the input filterincludes a plurality of second capacitors, and each second capacitor isconnected between one phase of the multi-phase AC input voltage and asecond filter common connection point.
 16. The method of claim 15wherein the input filter further includes a second common mode capacitorconnected between the second filter common connection point and thecommon connection.
 17. The method of claim 16 further comprising thestep of providing a first DC common mode inductor connected in series onthe DC bus between the DC bus capacitance and the inverter section. 18.The method of claim 17 further comprising the step of providing a secondDC common mode inductor connected in series on the DC bus between theconverter section and the DC bus capacitance.
 19. The method of claim 18further comprising the step of providing an AC common mode inductorconnected in series on each phase of the multi-phase AC input voltagebetween the input filter and the converter section.
 20. The method ofclaim 14 further comprising the step of filtering radiated emissionswith a radiated emissions shield extending over the input filter, theinverter section, and the output filter.